The aerial requires 12Vpower, but I think the RCD10 provides the power via the coaxial, so I didn’t connect the 12v power lead from the JVC aerial to anything. I have great FM and DAB reception, but no longer have any AM reception, I don’t know if that is because the aerial is not getting enough power, or the splice. If you are installing an RCD510 without DAB you shouldn't have this problem because you don't need to change the aerial and therefore your AM reception should be unchanged. As I now have DAB it doesn't matter that AM doesn't work.
Only just noticed this post. You are not getting AM because the JVC aerial is not capable of accepting power via the coaxial cable. Thus your FM & DAB reception are not as good as they ought to either. For the HAL-2 to work properly, the power cable MUST be connected to +12V. Thanks, dabonwheels